The present invention relates to an armrest device in a chair.
JP2005-211245A and JP2002-51871A disclose an armrest device in which an elongate hole is formed in an armrest base plate, a plurality of grooves being formed on each edge of the elongate hole, an elastic member being provided to press the side edge of the elongate hole on a support provided on the upper end of an armrest support rod for supporting an armrest to allow the armrest base plate to move with respect to the armrest support rod, the elastic member elastically engaging in the groove to provide stepwise resistant force of the armrest base plate. However, the grooves on the side edge of the elongate hole make movement of the armrest base plate unsmooth.
In JP2005-211245A, a pair of engagement pins is provided on each side of the elastic member and pressed onto the side edge of the elongate hole, so that the number of parts increases and assembling becomes more complicated.
In JP2002-51871A, the elastic member comprises a pair of bow-like members which are held by an armrest bracket. To keep rigidity and durability of the bow-like members, it is necessary to pay special attention to determine the material and shape thereof.
JP2005-192766A discloses an armrest device by which an armrest can be moved and turned. But the structure therefor makes the armrest device larger, and there are problems that the number of parts increases and its assembling becomes more complicated.
JP9-173178A, JP2000-279268A and JP2005-185619A disclose an armrest device in a chair, comprising a lower support rod extending upright from the side of a seat and an upper support rod having an armrest on the upper end to allow the upper support rod to slide with respect to the lower support rod up and down, an operating lever having an operating portion which projects from the side of the upper support rod, the operating lever being operated to move an engagement shaft or pin in the upper support rod being moved back and forth to allow the engagement shaft to engage in any one of multi-stage engagement portions extending from a vertical elongate portion in the lower support rod thereby holding the upper support rod at a desired height.
In JP9-173178A and JP2000-279268A, the operating portion and an extension for moving the engagement shaft back and forth are integrally formed like a reversed U-shape. The operating lever is pivotally mounted to the upper support rod with a pin at a curved portion of the U-shape. The distance between a pivot and an acting point is long. During operation, excessive force acts onto the operating portion, so that the pivot and/or extension is likely to be easily deformed or damaged. It is necessary to make the member from high-rigidity material.
In JP2005-185619A, an operating knob presses the upper end of an operating rod as pivoting lever rearwards. A pin at the lower end of the operating rod is pivoted back and forth about the middle to allow the pin to engage in and disengage from the engagement hole.
The rear end of the knob merely contacts the front face of the upper end of the operating rod, but the knob is surely connected to the operating rod. If the pin should be caught on one of the engagement holes to make the operating rod impossible to return, the knob will not be operative. Means for limiting back-and-forth movement of the knob becomes more complicated.
JP2005-185629A discloses an armrest device that enables the height of an armrest to be adjusted in a chair. In the device, an arm pad support rod for supporting an arm pad slidably fits up and down in a tubular armrest support rod which stands from the side of a seat. A knob at the upper part of the arm pad support rod is pressed to move the upper part of an operating rod pivotally mounted in the middle in the arm pad support rod to move a pin at the lower part of the operating rod forwards to allow the pin to disengage from any one of multi-stage engagement grooves at the side of a guide sleeve in the armrest support rod. After the armrest and armrest support rod are moved to a desired height, a hand is released from the knob, so that the pin is moved rearwards by force of urging means to engage in any one of the engagement grooves.
The guide sleeve comprises two semicylindrical pieces in which outward flanges contact the upper end of the armrest support rod.
However, the guide sleeve merely comprises two semicylindrical pieces which pressingly fit in the armrest support rod. When the armrest is elevated, the guide sleeve is likely to be released upwards from the armrest support rod.
To prevent such problem, the guide sleeve is fixed to the armrest support rod with screws, but heads of the screws are exposed to make its appearance poorer and working for mounting the screws is more complicated to make its assembly more difficult.